#include "HashArchivo.h"

void HashArchivo::SHA1Reset(SHA1Context *context)
{
    context->Length_Low             = 0;
    context->Length_High            = 0;
    context->Message_Block_Index    = 0;

    context->Message_Digest[0]      = 0x67452301;
    context->Message_Digest[1]      = 0xEFCDAB89;
    context->Message_Digest[2]      = 0x98BADCFE;
    context->Message_Digest[3]      = 0x10325476;
    context->Message_Digest[4]      = 0xC3D2E1F0;

    context->Computed   = 0;
    context->Corrupted  = 0;
}

int HashArchivo::SHA1Result(SHA1Context *context)
{

    if (context->Corrupted)
    {
        return 0;
    }

    if (!context->Computed)
    {
        SHA1PadMessage(context);
        context->Computed = 1;
    }

    return 1;
}

void HashArchivo::SHA1Input(     SHA1Context         *context,
                    const unsigned char *message_array,
                    unsigned            length)
{
    if (!length)
    {
        return;
    }

    if (context->Computed || context->Corrupted)
    {
        context->Corrupted = 1;
        return;
    }

    while(length-- && !context->Corrupted)
    {
        context->Message_Block[context->Message_Block_Index++] =
                                                (*message_array & 0xFF);

        context->Length_Low += 8;
        /* Force it to 32 bits */
        context->Length_Low &= 0xFFFFFFFF;
        if (context->Length_Low == 0)
        {
            context->Length_High++;
            /* Force it to 32 bits */
            context->Length_High &= 0xFFFFFFFF;
            if (context->Length_High == 0)
            {
                /* Message is too long */
                context->Corrupted = 1;
            }
        }

        if (context->Message_Block_Index == 64)
        {
            SHA1ProcessMessageBlock(context);
        }

        message_array++;
    }
}

void HashArchivo::SHA1ProcessMessageBlock(SHA1Context *context)
{
    const unsigned K[] =
    {
        0x5A827999,
        0x6ED9EBA1,
        0x8F1BBCDC,
        0xCA62C1D6
    };
    int         t;
    unsigned    temp;
    unsigned    W[80];
    unsigned    A, B, C, D, E;

    for(t = 0; t < 16; t++)
    {
        W[t] = ((unsigned) context->Message_Block[t * 4]) << 24;
        W[t] |= ((unsigned) context->Message_Block[t * 4 + 1]) << 16;
        W[t] |= ((unsigned) context->Message_Block[t * 4 + 2]) << 8;
        W[t] |= ((unsigned) context->Message_Block[t * 4 + 3]);
    }

    for(t = 16; t < 80; t++)
    {
       W[t] = SHA1CircularShift(1,W[t-3] ^ W[t-8] ^ W[t-14] ^ W[t-16]);
    }

    A = context->Message_Digest[0];
    B = context->Message_Digest[1];
    C = context->Message_Digest[2];
    D = context->Message_Digest[3];
    E = context->Message_Digest[4];

    for(t = 0; t < 20; t++)
    {
        temp =  SHA1CircularShift(5,A) +
                ((B & C) | ((~B) & D)) + E + W[t] + K[0];
        temp &= 0xFFFFFFFF;
        E = D;
        D = C;
        C = SHA1CircularShift(30,B);
        B = A;
        A = temp;
    }

    for(t = 20; t < 40; t++)
    {
        temp = SHA1CircularShift(5,A) + (B ^ C ^ D) + E + W[t] + K[1];
        temp &= 0xFFFFFFFF;
        E = D;
        D = C;
        C = SHA1CircularShift(30,B);
        B = A;
        A = temp;
    }

    for(t = 40; t < 60; t++)
    {
        temp = SHA1CircularShift(5,A) +
               ((B & C) | (B & D) | (C & D)) + E + W[t] + K[2];
        temp &= 0xFFFFFFFF;
        E = D;
        D = C;
        C = SHA1CircularShift(30,B);
        B = A;
        A = temp;
    }

    for(t = 60; t < 80; t++)
    {
        temp = SHA1CircularShift(5,A) + (B ^ C ^ D) + E + W[t] + K[3];
        temp &= 0xFFFFFFFF;
        E = D;
        D = C;
        C = SHA1CircularShift(30,B);
        B = A;
        A = temp;
    }

    context->Message_Digest[0] =
                        (context->Message_Digest[0] + A) & 0xFFFFFFFF;
    context->Message_Digest[1] =
                        (context->Message_Digest[1] + B) & 0xFFFFFFFF;
    context->Message_Digest[2] =
                        (context->Message_Digest[2] + C) & 0xFFFFFFFF;
    context->Message_Digest[3] =
                        (context->Message_Digest[3] + D) & 0xFFFFFFFF;
    context->Message_Digest[4] =
                        (context->Message_Digest[4] + E) & 0xFFFFFFFF;

    context->Message_Block_Index = 0;
}

void HashArchivo::SHA1PadMessage(SHA1Context *context)
{
    if (context->Message_Block_Index > 55)
    {
        context->Message_Block[context->Message_Block_Index++] = 0x80;
        while(context->Message_Block_Index < 64)
        {
            context->Message_Block[context->Message_Block_Index++] = 0;
        }

        SHA1ProcessMessageBlock(context);

        while(context->Message_Block_Index < 56)
        {
            context->Message_Block[context->Message_Block_Index++] = 0;
        }
    }
    else
    {
        context->Message_Block[context->Message_Block_Index++] = 0x80;
        while(context->Message_Block_Index < 56)
        {
            context->Message_Block[context->Message_Block_Index++] = 0;
        }
    }

    context->Message_Block[56] = (context->Length_High >> 24) & 0xFF;
    context->Message_Block[57] = (context->Length_High >> 16) & 0xFF;
    context->Message_Block[58] = (context->Length_High >> 8) & 0xFF;
    context->Message_Block[59] = (context->Length_High) & 0xFF;
    context->Message_Block[60] = (context->Length_Low >> 24) & 0xFF;
    context->Message_Block[61] = (context->Length_Low >> 16) & 0xFF;
    context->Message_Block[62] = (context->Length_Low >> 8) & 0xFF;
    context->Message_Block[63] = (context->Length_Low) & 0xFF;

    SHA1ProcessMessageBlock(context);
}

int HashArchivo::bin_to_base64(char *src,int src_len,char* ptr)
{
    char base64[]="ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
    int i,k;
    int triplets,rest;
    char *s;
    s=ptr;

    triplets = src_len/3;
    rest = src_len%3;
    for(i=0;i<triplets*3;i+=3){
        k = (((unsigned char) src[i])&0xFC)>>2;
        *ptr=base64[k];ptr++;

        k = (((unsigned char) src[i])&0x03)<<4;
        k |=(((unsigned char) src[i+1])&0xF0)>>4;
        *ptr=base64[k];ptr++;

        k = (((unsigned char) src[i+1])&0x0F)<<2;
        k |=(((unsigned char) src[i+2])&0xC0)>>6;
        *ptr=base64[k];ptr++;

        k = (((unsigned char) src[i+2])&0x3F);
        *ptr=base64[k];ptr++;
    }
    i=triplets*3;
    switch(rest){
        case 0:
            break;
        case 1:
            k = (((unsigned char) src[i])&0xFC)>>2;
            *ptr=base64[k];ptr++;

            k = (((unsigned char) src[i])&0x03)<<4;
            *ptr=base64[k];ptr++;

            *ptr='=';ptr++;

            *ptr='=';ptr++;
            break;
        case 2:
            k = (((unsigned char) src[i])&0xFC)>>2;
            *ptr=base64[k];ptr++;

            k = (((unsigned char) src[i])&0x03)<<4;
            k |=(((unsigned char) src[i+1])&0xF0)>>4;
            *ptr=base64[k];ptr++;

            k = (((unsigned char) src[i+1])&0x0F)<<2;
            *ptr=base64[k];ptr++;

            *ptr='=';ptr++;
            break;
    }

    return ptr-s;
}


unsigned int HashArchivo::IntFixEndiannes (char *c) {
    int i;
    char *p = (char *)&i;

    if (is_bigendian()) {
        p[0] = c[0];
        p[1] = c[1];
        p[2] = c[2];
        p[3] = c[3];
    } else {
        p[0] = c[3];
        p[1] = c[2];
        p[2] = c[1];
        p[3] = c[0];
    }

    return i;
}

string HashArchivo::GenerarHash( string filename )
{
    int n;
    char buf[1024];
    memset( buf, 0, sizeof(buf) );

    char result[31];
    memset( result, 0, sizeof(result) );

    SHA1Context sha;

    SHA1Reset(&sha);

    int fd = open( filename.c_str(), O_RDONLY );
    while ( ( n = read( fd, buf, sizeof( buf ) ) ) > 0 ) {
        SHA1Input(&sha, (const unsigned char *) buf, n );
    }
    close( fd );

    SHA1Result(&sha);

    for (n = 0; n < 5; n++) 
        sha.Message_Digest[n] = IntFixEndiannes( (char*)&sha.Message_Digest[n] );
    memset( buf, 0, sizeof(buf) );

    bin_to_base64( (char*)sha.Message_Digest, 20, buf);
    memcpy( result, buf, 30);
    result[31] = '\0';
    return string( result );
}

